Ordinarily, percussion processors for electronic musical instruments, such as electronic organs or the like, include parallel RC networks for supplying the keyers with a turn-on voltage which is applied only momentarily to simulate a pizzicato or percussion touch, even though the keyboards may be played with a legato technique. Such keyers include the keyers used for producing percussion effects as well as the chiff keyers used in conjunction with the flute keyers to produce the desired pipe organ sounds from the instrument. A parallel percussion processor of this type for producing the desired percussion effects for all of the different tones capable of reproduction by the percussion or chiff keyers requires a large number of resistors, capacitors, and complicated interconnecting wiring.
In an attempt to reduce the number of interconnecting wires between a keyboard and keyers of an electronic organ, time-division multiplex techniques have been developed to sequentially and repetitively scan the key switches and control switches to produce a single repetitive sequence of time-division multiplexed pulses on a single output lead for further processing by the keyers of the organ. While this substantially reduces the amount of wiring needed for producing ordinary tones in the organ, it still has been necessary to demultiplex this information and to drive a large number of parallel RC keyer circuits to produce percussion or chiff effects. This requires additional demultiplexing circuits with a large amount of interwiring and, of course, capacitors and resistors for each of the percussion note inputs to the percussion and chiff keyers.
It is desirable to utilize percussion processing in a time-division multiplexed electronic organ which eliminates the necessity for using RC circuits to produce percussion effects and which is capable of operating upon the serial time-division multiplexed signal to permit it to be used without first demultiplexing it to drive a conventional keyer to produce percussion and chiff effects.